The possibility of bugs is something that the defence can argue - the court would need to find beyond reasonable doubt that the defendant was guilty. It's certainly not the responsibility of manufacturer to provide perfect or imperfect certainty about the data, but it's the prerogative of the jury to decide the trustworthiness of that data.
I assume that a reasonable justice system wouldn't sentence someone based on a singular piece of evidence. True facts reinforce each other; false claims oppose the truth. Therefore if the data was incorrect, hopefully there would be other pieces of evidence that would contradict the data.
Software has bugs, what if the data implicated him but was incorrect? Of course bugs in a pacemaker means bigger problems... but you get my point.